148 S/iatv — Structure of the Flozvers in 



5. The microspores of the evident flowers undergo a great 

 increase in size at the time of flowering ; the same is true to a 

 less degree of the microspores of the two other types of flower. 



6. Contrary to the condition described for the other cleis- 

 togamic flowers, the walls of the microspores are very thick. 



7. A canal is present in the pistil leading from the ovarian 

 cavity to the e.xterior. At the base of the style the lumen 

 is sometimes filled by hairy outgrowths from the surrounding 

 tissue. A similar condition is found in P. paucifolia. 



8. Glandular hairs, found sparsely on the ovary of the evi- 

 dent flowers, are present in great abundance on that of the 

 subterranean ones, pointing to specialization of some kind, 

 possibly a capacity for absorption. 



9. The indurated portion of the testa is derived from the 

 inner cell-layer of the primine. 



10. The chasmogamic flowers of P. paucifolia exhibit a 

 condition of initial gymandry combined with the complete 

 coalescence of stamens and petals. 



1 1. The hypothesis that cleistogamic flowers are developed, 

 to preserve the species when the chasmogamic ones fail, is un- 

 satisfactory, because these are produced each year abundantly. 



1 2. The hypothesis that this development is due to lack of 

 light or similar causes is probably partially true, but is insuf- 

 ficient, because cleistogamic flowers are produced in great 

 abundance on healthy plants in the warm and sunny period 

 of midsummer. 



13. Neither can this development be explained as a device 

 for developing protected fruits, for although the plant suffers 

 from grazing animals, these aerial flowers appear among the 

 foliage where the danger is greatest. 



14. The cleistogamic flowers, like those of other species, 

 develop seed more rapidly than do the conspicuous ones. It 

 is believed that the purpose of their existence is the economi- 

 cal and speedy production of seed. 



